High voltage capacitors are often employed in implantable medical devices. Implantable cardioverter defibrillators (“ICDs”), for instance, normally employ a capacitor bank that contains two to four capacitors connected in series to achieve a high therapeutic voltage for shock delivery. In certain cases, for instance, the capacitor may contain a metal foil (e.g., aluminum foil) in combination with a liquid electrolyte having a relatively neutral pH. One problem, however, is that these types of electrolytes tend to increase the equivalent series resistance (“ESR”) of the capacitor, which can result in wasted energy when the bank delivers a therapeutic high voltage treatment. As such, a need currently exists for improved capacitors for use in a medical device, such as a defibrillator.